diff --git a/include/gint/hardware.h b/include/gint/hardware.h
index 6044ec8..6a252a2 100644
--- a/include/gint/hardware.h
+++ b/include/gint/hardware.h
@@ -111,6 +111,8 @@ void hw_detect(void);
 #define HWCALC_FX9860G_SLIM  7
 /* fx-CP 400 */
 #define HWCALC_FXCP400       8
+/* fx-CG 100, successor to the CG-50 in the Prizm family. Also Graph Math+ */
+#define HWCALC_FXCG100       9
 
 /*
 **  Keyboard
diff --git a/src/kernel/hardware.c b/src/kernel/hardware.c
index 8a02815..3340513 100644
--- a/src/kernel/hardware.c
+++ b/src/kernel/hardware.c
@@ -127,10 +127,28 @@ void hw_detect(void)
 	gint[HWCPUVR] = PVR;
 	gint[HWCPUPR] = PRR;
 
-	/* Tell Prizms apart from fx-CG 50 by checking the stack address*/
 	uint32_t stack;
 	__asm__("mov r15, %0" : "=r"(stack));
-	gint[HWCALC] = (stack < 0x8c000000) ? HWCALC_PRIZM : HWCALC_FXCG50;
+	char const *version = (void *)0x80020020;
+	char const *osdate = (void *)0x80b5ffe0;
+
+	/* Tell Prizms apart from fx-CG 50 by checking the stack address*/
+	if(stack < 0x8c000000) {
+		gint[HWCALC] = HWCALC_PRIZM;
+	}
+	/* Tell Math+/fx-CG 100 apart from CG-50 by checking OS version + date.
+	   CG-50 OS versions use OS 3. Math+, for some reason, rewinds back to OS 1
+	   and got updated to OS 2 in late 2024. We decide that we are on a CG-50 OS
+	   if the version is 3 and the date is 201x-2024. */
+	else {
+		/* All known CG-50 versions have date at this address due to the footer
+		   location. WARNING: not a future-proof address! */
+		char d0 = osdate[0], d1 = osdate[1], d2 = osdate[2], d3 = osdate[3];
+		bool cg50 = version[1] == '3' && d0 == '2' && d1 == '0' &&
+						(d2 == '1' || (d2 == '2' && d3 <= '4'));
+		gint[HWCALC] = cg50 ? HWCALC_FXCG50 : HWCALC_FXCG100;
+	}
+
 	gint[HWFS] = HWFS_FUGUE;
 
 	/* Tell the fx-CG emulator apart using the product ID */
diff --git a/src/kernel/kernel.c b/src/kernel/kernel.c
index c797ef5..3541e70 100644
--- a/src/kernel/kernel.c
+++ b/src/kernel/kernel.c
@@ -118,16 +118,18 @@ void kinit(void)
 
 	/* Create an arena in the OS stack as well, for VRAM and more data */
 	#if GINT_HW_CG && !defined(GINT_NO_OS_STACK)
-	static kmalloc_arena_t os_stack = { 0 };
-	os_stack.name = "_ostk";
-	os_stack.is_default = true;
-	if(gint[HWCALC] == HWCALC_PRIZM || gint[HWCALC] == HWCALC_FXCG_MANAGER)
-		os_stack.start = (void *)0x880f0000;
-	else
-		os_stack.start = (void *)0x8c0f0000;
-	os_stack.end = os_stack.start + (350 * 1024);
-	kmalloc_init_arena(&os_stack, true);
-	kmalloc_add_arena(&os_stack);
+	if(gint[HWCALC] != HWCALC_FXCG100) {
+		static kmalloc_arena_t os_stack = { 0 };
+		os_stack.name = "_ostk";
+		os_stack.is_default = true;
+		if(gint[HWCALC] == HWCALC_PRIZM || gint[HWCALC] == HWCALC_FXCG_MANAGER)
+			os_stack.start = (void *)0x880f0000;
+		else
+			os_stack.start = (void *)0x8c0f0000;
+		os_stack.end = os_stack.start + (350 * 1024);
+		kmalloc_init_arena(&os_stack, true);
+		kmalloc_add_arena(&os_stack);
+	}
 	#endif
 
 	/* Allocate world buffers for the OS and for gint */
diff --git a/src/kernel/osmenu.c b/src/kernel/osmenu.c
index c5173c0..5124b67 100644
--- a/src/kernel/osmenu.c
+++ b/src/kernel/osmenu.c
@@ -95,6 +95,11 @@ static os_menu_function_t *find_os_menu_function(void)
 
 void gint_osmenu_native(void)
 {
+#if GINT_OS_CG
+	if(gint[HWCALC] == HWCALC_FXCG100)
+		return;
+#endif
+
 // TODO: OS menu on fx-CP
 #if !GINT_OS_CP
 	__ClearKeyBuffer();
diff --git a/src/kernel/start.c b/src/kernel/start.c
index 26e4257..5159a92 100644
--- a/src/kernel/start.c
+++ b/src/kernel/start.c
@@ -42,8 +42,9 @@ int8_t gint_restart = 0;
 /* gint_setrestart(): Set whether to restart the add-in after exiting */
 void gint_setrestart(int restart)
 {
-	/* There is now return-to-menu so no restart on CP */
-	gint_restart = restart && !GINT_OS_CP;
+	/* No restart on the machines for which there is no return-to-menu, i.e. on
+	   fx-CP and on the fx-CG 100. */
+	gint_restart = restart && !GINT_OS_CP && gint[HWCALC] != HWCALC_FXCG100;
 }
 
 /* Return value of main() */
diff --git a/src/kernel/syscalls.S b/src/kernel/syscalls.S
index a13f2b6..94bc19f 100644
--- a/src/kernel/syscalls.S
+++ b/src/kernel/syscalls.S
@@ -217,7 +217,7 @@ _gint_get_CASIOWIN_API:
 	.long 0x1dab, 0x8024003c  /* BFile_GetPos */
 	.long 0x1daf, 0x8024025e  /* BFile_Write */
 	.long 0x1dac, 0x80240082  /* BFile_Read */
-	.long 0x1db6, 0           /* BFile_FindFirst */
+	.long 0x1db6, 0x80240888  /* BFile_FindFirst */
 	.long 0x1db8, 0x80240b06  /* BFile_FindNext */
 	.long 0x1dba, 0x80240c10  /* BFile_FindClose */
 	.long 0x08d9, 0x800b130c  /* Timer_Install */
@@ -227,7 +227,7 @@ _gint_get_CASIOWIN_API:
 	.long 0x12c6, 0           /* PutKeyCode */
 	.long 0x12bf, 0x8017be56  /* GetKeyWait */
 	.long 0x12c7, 0           /* ClearKeyBuffer */
-	.long 0x01e6, 0           /* GetVRAMAddress */
+	.long 0x01e6, 0x8004579a  /* GetVRAMAddress */
 	.long 0x1e6e, 0           /* SetQuitHandler */
 	.long 0x1839, 0           /* PowerOff */
 	.long 0x1187, 0           /* Reset */
diff --git a/src/render-cg/dvram.c b/src/render-cg/dvram.c
index aac777a..7f9f287 100644
--- a/src/render-cg/dvram.c
+++ b/src/render-cg/dvram.c
@@ -97,16 +97,15 @@ bool dvram_init(void)
 {
 	int const MARGIN = 32;
 
+	char const *arena = NULL;
+	if(kmalloc_get_arena("_ostk"))
+		arena = "_ostk";
+
 	/* Leave MARGIN bytes on each side of the region; this enables some
 	   important optimizations in the image renderer. We also add another
 	   32 bytes so we can manually 32-align the region */
-	uint32_t region = (uint32_t)kmalloc(DWIDTH*DHEIGHT*2 + MARGIN*2 + 32,
-#if !defined(GINT_NO_OS_STACK)
-		"_ostk"
-#else
-		NULL
-#endif
-	);
+	uint32_t region =
+		(uint32_t)kmalloc(DWIDTH*DHEIGHT*2 + MARGIN*2 + 32, arena);
 	if(region == 0)
 		return false;